Conventionally, hydrofluorocarbon (HFC) based refrigerants have been used as the refrigerants for heat pump devices and organic Rankine cycle devices. HFC-based refrigerants have an ozone layer depletion coefficient of zero, and have high thermal stability. However, HFC-based refrigerants have an extremely high global warming potential (GWP). As a result, the use of HFC-based refrigerants is undesirable from the viewpoint of global environmental protection.
Examples of known refrigerants having a low GWP include hydrofluoroolefin (HFO) and hydrochlorofluoroolefin (HCFO) based refrigerants. Patent Literature 1 (PTL 1) discloses a cooling cycle device which uses a refrigerant containing an HFO as the base component. In PTL 1, a tetrafluoropropene (HFO1234yf) is used as the HFO-based refrigerant.
HFO and HCFO compounds have a double bond within the molecular structure. As a result, HFO-based refrigerants and HCFO-based refrigerants have lower chemical stability than HFC refrigerants. When HFO and HCFO compounds are used as refrigerants, a problem arises in that the effects of water and oxygen can cause cleavage and decomposition of the compounds, generating substances containing acids as the main components. Substances containing acids as the main components can degrade the materials used in the cooling cycle device and the refrigerating machine oil, causing a deterioration in the performance of the cooling cycle device.
In order to address the above problem, the cooling cycle device disclosed in PTL 1 comprises an adsorption device within the cooling cycle. This adsorption device contains an adsorbent that can adsorb substances containing hydrofluoric acid (HF) as the main component. The adsorbent comprises a zeolite, silica, or ion exchange resin or the like the main component.